We actually may have no idea what triggers our migraines, new research suggests.

Findings from Wake Forest Baptist Medical Center show that migraine triggers are difficult to determine without undergoing more formal testing.

"Correctly identifying triggers allows patients to avoid or manage them in an attempt to prevent future headaches," study researcher Timothy T. Houle, Ph.D., assistant professor of anesthesia and neurology at Wake Forest Baptist Medical Center, said in a statement. "However, daily fluctuations of variables -- such as weather, diet, hormone levels, sleep, physical activity and stress -- appear to be enough to prevent the perfect conditions necessary for determining triggers."

Researchers published two studies on the subject in the journal Headache. In one of them, they noted that there must be three criteria in order for something to be reliably identified as a migraine trigger. The first is "constancy of the sufferer," the second is "constancy of the trigger effect" and the third is "constancy of the trigger presentation."

In the other study, researchers examined nine female study participants who were diagnosed with migraine (some with aura, some without). They kept a daily diary for three months, and also took questionnaires to analyze their stress levels and common stressors. Urine was collected from the women every morning to test their hormone levels during the study, and weather information was analyzed for the study period.

Recently, a study in the journal Neurology showed that people may not be as "in tune" with their migraine triggers as they think, especially considering how pervasive traditional triggers are in everyday life, Everyday Health reported.

More than 29.5 million people in the U.S. get migraines, and they are more common in women, according to the National Headache Foundation. They can occur with an aura -- which is a visual disturbance -- or without, and symptoms often also include nausea, light/sound sensitivity and head pain.